Uniform magnetic field of the planar coil with new winding structure for displacement-insensitive WPT

In near field wireless power transfer (WPT), the uniformity of magnetic field distribution near the transmitting coil is needed since it would affect the stability of transfer efficiency when the receiving coil is moving. In this paper, we proposed a new coil structure constructed of 3 or more spiral coils in series based on the relationship between current distribution and magnetic field distribution. Compared with previous literatures, this proposed coil can generate a more uniform magnetic field distribution.